Task Outcome Summary

• DATA STATUS: Nominal
• TASK OUTCOME: Nominal

Abstract

Analysis

The data were reduced with version 2.41 of the MIPS DAT. The non-default parameters used included turning off the correction for electronic nonlinearity, specifying the dark and illumination correction for this campaign, and specifying the 70µm parameter file. The data were combined using a custom IDL routine which includes the following steps:

• Throw out the first DCE after each stim DCE to reduce the effect of the stim latent.
• Measure the median background level in the good part of side A, and subtract it from the whole image (this is a simplified way of removing the stim latent from the image).
• Apply integer pixel shifts (determined using the WCS) to align the images.
• Apply sigma-clipping (typically 3 sigma) and average the remaining pixels.

The mosaicked images (a combination of 25 DCEs each) are shown in Figure 1. The disparity between the noise properties of side A (the "good" side, on which the source is located) and side B is readily apparent.

Figure 1: 70µm images of HD 163588.

Photometry was performed on the mosaicked images with a private IDL program, and its results were often checked against the APPHOT program in IRAF. The parameters used were an aperture radius of 3 pixels and a sky annulus of 4-8 pixels. Sky values that deviated by more than 3 sigma from the median were rejected. The aperture correction was determined to be 1.27 based on a STinyTim PSF. Noise measurements include only the standard deviation of the pixels in the sky annulus.

Results

The measured photometry can be found in the table below. Note that the measurements are made on data calibrated by dividing by a stimflash, and so the "MIPS₇₀ Unit" refers to a ratio of the sky image to the stimflash. Due to the median-subtraction process described above, the residual background should be close to 0, which accounts for the small value of and large error on the background measurements in the table. The final calibration factor quoted in the abstract is the average of the two measurements in the table.

N.B. This is the first campaign in which the photometry mode was adjusted to keep the source on the good side of the array, which accounts for the larger number of images in each mosaic and the increased integration time in the table below.

Photometry
Target	Predicted Flux	Predicted Sky	Measured Flux	Measured Sky	Calibration Factor	Integration Time
	(Jy)	(MJy/sr)	(MIPS70 Unit)	(MIPS70 Unit)	(MIPS70/Jy)	(MIPS sec.)
HD163588	0.329	4.8	0.24±0.02	0.0002±0.0028	0.72±0.06	75
HD163588	0.329	4.8	0.19±0.02	0.0004±0.0022	0.58±0.05	75

The surface brightness calibration factor was determined by averaging these results with those from Campaign Q, the only other campaign which has good anneals and the same bias settings. The average of the 4 flux measurements in these 2 campaigns is 0.226 MIPS₇₀Unit. The pixel size in all cases was 9.89 arcsec. The calibration factor (CF) is thus:

CF = 0.329 Jy * 1e6 µJy/Jy / 0.226 MIPS₇₀Unit / (9.89 arcsec)² = 1.49 * 10³µJy/arcsec²/MIPS₇₀Unit

Conclusions

The target was observed successfully and good S/N obtained. A calibration factor was successfully measured.

Output and Deliverable Products

The calibration factor is delivered in this report.

Actions Following Analysis